This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Aim 1 Define the gene expression profile of endothelial progenitor cells of obese insulin resistant compared with obese non-insulin resistant and lean AA womenDefine expression of genes related to oxidative stress such as NADPH oxidase, endothelial nitric oxide synthase and copper zinc superoxide dismutase Define expression of genes related to insulin action and sympathetic nervous system activation Determine the relationship between antioxidant gene expression in EPCs among the three groups and levels of oxidative stress Hypothesis1: We hypothesize that the relationship between vascular stiffness (augmentation index) and the number of circulating endothelial progenitor cells shown in our earlier studies, is partly mediated through oxidative stress with up regulation of genes modulating oxidative stress. We anticipate that persistent oxidative stress will lead to exhaustion of the antioxidant mechanisms within the EPCs which will eventually impair the ability of these cells to assist in endothelial repair and maintenance of endothelial function. Furthermore, we hypothesize that there will be a difference in the gene expression profile among the three groups of women as a result of the response to oxidative stress